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Unread 07-29-2014, 03:53 PM   #1
transguy1
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wj 4.7 helppppppp

hey new to this forum hope im posting in right place! anyway long story short bought 2000 jeep grand Cherokee with a 4.7 it lost a lifter ended up bending the valve sooo...
replaced the head/gasket as well as new gasket on other side and timing chain and componets, spark plugs correct gap all new gaskets etc..
The motor will fire up on a cold start first try with a very very low idle and stay idling very rough for about 15 mins then stall.. it will then crank very long (have to give throttle) then start.. I had a 02 sensor 1 code along with an injector 6 and 8 circ malfunction .. I replaced tps still nothing! ive checked fuel pressure, plugs, coils, injectors (resistance) everything checks out cleaned tb and iac motor IM GOING NUTS AT THIS POINT plzzz helppppppp!!!!!!!!!

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Unread 07-29-2014, 04:01 PM   #2
transguy1
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forgot to say I replced the 02s as well!
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Unread 07-29-2014, 04:06 PM   #3
JMZ101586
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Sounds like your out of time or low on compression. Did you check the heads block cly for cracks?
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Unread 07-29-2014, 04:15 PM   #4
transguy1
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yes heads and block were good and timing was dead on the money cranked over by hand several times to make sure
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Unread 07-29-2014, 04:29 PM   #5
asatxj
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Cam and or Crank position sensor? Have you plugged in a code reader?
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Unread 07-29-2014, 04:39 PM   #6
transguy1
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Quote:
Originally Posted by asatxj View Post
Cam and or Crank position sensor? Have you plugged in a code reader?
yeah no codes for either I had pulled cam sensor cleaned well before fresh oil went in but never touched crank sensor because no codes
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Unread 07-29-2014, 06:19 PM   #7
cowgirllup
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My crank sensor never threw a code just had problems like you're having where it idles like crap cranks over a thousand times before starting and actually wouldn't start at all for awhile. Took the old sensor out and it was completely shot. Not a terribly expensive fix but definitely worth it.

2000 WJ--Just bought! trying to decide how to mod.
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Unread 07-30-2014, 07:15 AM   #8
transguy1
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Quote:
Originally Posted by cowgirllup View Post
My crank sensor never threw a code just had problems like you're having where it idles like crap cranks over a thousand times before starting and actually wouldn't start at all for awhile. Took the old sensor out and it was completely shot. Not a terribly expensive fix but definitely worth it.

2000 WJ--Just bought! trying to decide how to mod.
thanks think I will that a shot going to do a comp test just to make sure once again my compression is good
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Unread 07-30-2014, 07:56 AM   #9
JMZ101586
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It's highly unlikely you had a good sensor replace the head and now it went bad. It's far more likely something got fubared on the reinstall.
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Unread 07-30-2014, 03:49 PM   #10
transguy1
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Quote:
Originally Posted by JMZ101586 View Post
It's highly unlikely you had a good sensor replace the head and now it went bad. It's far more likely something got fubared on the reinstall.
well the jeep was bought like this not running from my shop I have absolutely no backgroung info on it .. im just trying to get it going!
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Unread 07-30-2014, 05:48 PM   #11
akoutdoors1
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Most resources caution that it is VERY easy to mess up timing gears on this install. Compression test should help you decide next move.
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Unread 08-05-2014, 04:33 PM   #12
transguy1
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UPDATE* I went over compression again and found 0 in number 6 cylinder (guessing that was why I got my injector code in #6) any way pulled head off and found a bent valve .. replaced it checked over head once again new gasket etc.. got it back together today compression 155ish give or take across the board.. started right up idled like a champ no more misfire .. let it run got it hot put in reverse and she dies .. cranks and cranks but no start unless throttle is given?! no cel .. anyone???
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Unread 08-05-2014, 04:34 PM   #13
transguy1
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seems to only start cold*
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Unread 08-05-2014, 05:40 PM   #14
SuperDragpack
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I would now investigate the crank sensor. Easy job to do compared to what you have done already.

They will often fail when hot/warm - but so will lots of other sensors - although very few will completely prevent the engine from starting.

I had a crank sensor fail the other week on a 2000 V8. It would start and run perfectly, then occasionally (once every few days) the idle would jump up and down. Sometimes it would cut out and not restart for 10 minutes. Other days it would be fine whilst other days it would be in and out of limp mode. The only codes it would ever give were transmission speed sensor errors - but even that was rare. It was actually worse when I had a trailer plugged in - like it was dropping the voltage just that small amount which upset the sensor.

Anyway, 5 minutes to change the sensor and it was a champ again.

If it helps diagnose this issue - I discovered that a failed or disconnected crank sensor will still allow a spark but will NOT fire the injectors at all.
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Unread 08-06-2014, 11:21 AM   #15
transguy1
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can you tell if sensor is bad by looking at it? because I have good voltage to it and everything checks out on my meter ..
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